This invention relates to the monitoring of a liquid such as water through a pressurized opaque line. In certain types of industrial or commercial environments, it is often necessary to maintain a reservoir or tank of water or other liquid full or at a desired level at all times in order to provide for humidity control or similar situations. Generally, in such situations, the water or liquid in the tank is constantly being used, and therefore a constant flow of liquid into the tank must be provided. For example, in a lumber kiln, there is provided a "wet bulb box" within the kiln which receives a supply of water from a pressure line, which water is picked up by a wick and evaporated into the atmosphere of the room by the flow of air thereover. The water is constantly being used, and therefore must constantly be supplied to maintain the wet bulb box at a fluid level that slightly overflows at all times (so operator can determine if sufficient water is present).
In certain installations, this is a relatively easy task. For example, imagine a water trough in which the water is constantly being drained out an opening in the lower area thereof. It is a relatively simple matter to adjust the valve of a faucet which delivers water into the trough to supply water at the same rate at which it is being withdrawn. On the other hand, imagine a watering trough in which the operator cannot visually see the output from the faucet into the trough, as is the case in a reservoir of the type in which the supply line to the reservoir actually introduces the water below the water level. To further complicate the situation, in a kiln or similar atmosphere, it may be dangerous for an operator to enter the kiln, if the temperature and moisture conditions are too high, to inspect the wet bulb box. Float valves have proven generally unsatisfactory because of their tendency to become clogged.
It therefore becomes highly desirable to be able to easily monitor and control the flow of water or liquid through the opaque pressurized feed line at a point outside of the kiln or other operating environment. This cannot be accomplished merely by making a portion of the feed line transparent, because in a pressurized line situation, the water always fills the feed line, and a visual inspection will not allow the operator to determine the rate of water flow.
It is this type of situation and problem which the present invention attempts to overcome. Short of elaborate controls, there is no known apparatus available for visually monitoring and controlling the flow of liquid through a pressurized line other than at the outlet thereof.
In general, the approach adopted in the present invention is to provide an interruption or intermediate outlet in a vertical section of an opaque pressurized liquid line allowing the liquid to fall at a prescribed rate through a transparent tube into a collection chamber. The collection chamber and transparent tube are sealed to the upstream and downstream portions of the conduit, as well as to each other. The sealing creates an "air lock, " which as used herein describes the condition which exists as the air pressure within the collection chamber and transparent tube increases as the inlet valve is opened and liquid begins to fill the collection chamber. Eventually the air pressure will overcome the back pressure created by the liquid in the downstream portion of the conduit and cause the liquid to flow out of the collection chamber at the same rate that it is being introduced through the inlet valve. Once an equilibrium situation is established, the level within the collection chamber remains the same unless back pressure in the downstream line or leakage of the air from the chamber occurs. Thus the air lock serves the dual purpose of keeping the transparent tube evacuated which would otherwise obstruct the visual monitoring of the fluid liquid flow, and of maintaining sufficient pressure in the line to move the liquid out of the collection chamber at the same rate at which it is entering. The fluid flow may vary from a lazy stream to individual droplets being emitted through the observation tube and into the collection chamber, however, because the transparent observation tube is kept free of liquid and is large enough that the liquid being emitted from the outlet of the upstream portion does not engage the sides thereof, a clear monitoring of the stream size therethrough is possible.
The apparatus according to the present invention then permits visual inspection and adjustment of the flow rate of the liquid, while maintaining pressurized system which ensures continuous flow at the prescribed rate to the desired destination. Toward this end, an interruption or intermediate enclosed outlet in the pressure line provides for the free fall of the liquid for a prescribed distance through which the liquid is surrounded only by the transparent tube and is thus visible. A control valve is interposed in the pressure line upstream (or even downstream) of the intermediate outlet to vary the flow of liquid therethrough as is necessary to maintain the proper level in the reservoir. A visual monitoring means downstream of the valve surrounds the intermediate outlet in sealing arrangement thereto and includes a collection chamber attached to the upstream end of the downstream portion of the conduit, which chamber has a volume considerably greater than the instantaneous volume of fluid collected therein at any one time. The collection chamber has an opening in the upper end thereof for receiving the incoming liquid stream therethrough. A length of transparent tubing connects the opening in the upper wall of the collection chamber with the downstream end of the upstream portion of the conduit. The transparent tube is of an inner diameter substantially greater than the inner diameter of the conduit and considerably smaller than the inner diameter of the collection chamber, however, the inner diameter of the transparent tube is large enough that the stream or droplets being emitted from the orifice of the upstream conduit do not engage the side walls as they expand at the outlet (in the case of droplets) or otherwise engage the side wall of the transparent tube in the case of a tube that is slightly askew from the vertical. Also, the diameter of the transparent tube should not be too large, because the collection chamber would have to be enlarged. The housing and transparent tubing are connected to the conduit around the interruption in substantially air tight arrangement. An air lock is provided in the chamber and transparent tubing, the volume of which is greater than the volume of the tubing. As a result of the air lock the fluid leaves the chamber at the same rate that it enters and the normal fluid level tends to remain within the collection chamber rather than rising up within the observation tube.
It is therefore an object of the present invention to visually monitor the flow of liquid through a pressurized line at a point upstream of the outlet thereof without interrupting the rate of flow therethrough.
It is another object of the present invention to provide a means for maintaining a constant level of liquid in a reservoir from which the liquid is constantly being removed, which liquid is being delivered to the reservoir through a pressurized opaque line, from a point remote from the reservoir.